Oscillating doctor for paper machines



March 6, 1951 w. LYON OSCILLATING DOCTOR FOR PAPER MACHINE 4Sheets-Sheet 1 Filed Aug. 27, 1947 TJi/lzl 0m Lyon,

INVENTOR.

BY fi March 6, 1951 w LYON 2,544,557

OSCILLATING DOCTOR FOR PAPER MACHINE Filed Aug. 27; 1947 4 Sheets-Sheet2 William Lyon IN VEN TOR.

March 6, 1951 w, LYON I 2,544,557

OSCILLATING DOCTOR FOR PAPER MACHINE Filed Aug. 27, 1947 4 Sheets-Sheet3 William Lyon,

IN VENTOR.

March 6, 1951 w. LYON OSCILLATING DOCTOR FOR PAPER MACHINE 4Sheets-Sheet 4 Filed Aug. 2'7. 1947 ZJZl/L'Gm Lyon,

INVENTOR.

Patented Mar. 6, i951 UNITED STATES PATENT 'OEF Fl CE 2,544,557SCILLATING'DOCTQR'FORPAPER FMACHINES f William Lyon, -Prestwich, near:Manchester, England, :assignor to :Messrs. -Walmsleys '(Bury) ...Ltd.,.Bury,.England, a British company Application August 27,1947,"Serial-'No. 770,807 In Great Britain March 1, 1945 9 Claims. (Cl.927.4)

Thisinvention relates to-paper machinery, and

more 'particularlyto. arrangements for control- 'ling the doctorbladeorblades used on the rolls of such machinery.

The art has long recognized the advisability of reciprocating ea-doctorblade :to avoid localized wear between the blade and the roll. Wherethis has been accomplished by gearing,- the mechanism 'is cumbersome-and-/interferes-with general servicing of the roll. IMOIGOVBI',positivetgearing between the roll and the reciprocating .mechanism forthe ,doctor'maintains acyclic fixedrelationship between the blade andthe roll surface resulting in a'localized wear pattern between the bladeand the roll. The prior-art has pro- ;posed hydraulic actuation as ameans of over,-

coming the difiiculties occasioned zby the useof gears but all sucharrangements have necessitated very substantial modification of thedoctor blade supports. Such modificationsare often in conflict with theintended application of the doctor, since the design .of the doctorblade support is dictatedbythetype .of roll to which the doctor isapplied. For example, a .doctor .blade support which would serve.excellently well on a .top pressrollis completely unsuitedto operatingon .a breast roll. The present invention there- .fore contemplates .ahydraulic actuating means which can beadapted to various .doctor bladeswith a minimum of modification in the design. Modern highspeed papermaking machines are already of great length, notwithstanding .the factthat the amountofspac'e allowedfor theoperators to-obtain access to thevarious parts of the machine has been cut down to the minimum.

Existing mechanical oscillating gear cannot be applied to many of 'theplaces where it isdesirable to oscillate the mechanism withoutinterfering with the operation of .the paper machine, or

alternatively making its operation dangerousfor the operators.

In the case of new machines, the designersare very reluctant to extendthe length vof the machine merely to provide facilities forfittingoscillators. vIt is therefore an additional object to provideanoscillating mechanism whichmay be applied either to existingequipments or to those newly manufactured, without interfering withspace requirements, and which will have a minimum of exposed parts so asto minimize the'risk of injury to the operators.

Since reciprocation of .the doctor blade during "periods when the trollis :at rest-would -.also -pro- .=duce excessive local wear,--it is ;a.further object around the breast 'roll as shownat I6..observedfrom'Figs. 1' and 2 that the reflective width of breast roll H5is sonearly equaltothe space between .the main side supports and 1 2thereis little orno space between'either of the to provide anarrangement .for discontinuing reciprocation during "such'periods.

Still :anotherobject is to provide such aldevice which is of simple,dependable and ruggedwon- :struction, and .which can .be manufacturedandinstalled at a :cost which .is low considering the objects .to besatisfied.

The above and other objectsand advantages of the invention will best beunderstood byrcfer- .ence to the following detailed specification. ofthe invention,- reference 'being had .to .the accomqpanying drawings, inwhich:

Fig. '1 is asectional elevation ota typicallpaper :machine showing theapplication of.theimproved doctorarrangement to the .breast roll,

Fig. 2 isra plan view of the same,

Fig-3 is a sectional view taken ontheflinet- -t *Fig. A is an enlarged-view.-of the v.rightehand .portion of Fig. 1, parts being'brokenaway..-for

clarity of illustration,

Fig. 5 is a'fragmenta'ryrsectional viewtaken .Fig; 6 isuarplanview oftheapplication .of the invention .to .an .upper press :roll 0f agpapermachine,

Fig. '7 is a side view of the same,

Fig. 8 is. a longitudinal sectional view .of :the self-reversinghydraulic/motor employed in. connection with the invention,

Fig-9 is a plan view of .saidmotonand Fig. 10 is a diagrammatic view 1of an arrange- 'ment .for'interrupting the oscillation whenever theassociated. roll is stationary.

Referring'now to Figs. 1 to 3 ofthe drawings, numerals -l0 and L2designate respectively the side frame-members of a typical form of.F'ourdrinier machine, between which :is ;.;journailed the breast rolll4,-by means :of -:journals (not shown). The 'wire of the machine passes:It: will be adjacent its opposite ends to.stub shafts 26rand 23 :eachof which .is .rotatably received in asbearing block of squarecross-section. Bearing block 36 at the left end of the doctor support(looking at Figs. 1 and 2) is slidably received within an upwardly opensquare pocket 32 of a support bracket 34 bolted to frame member It), sothat block 38 is held against rotation within said pocket but is freelyslidable therein to a limited extent. Anti-friction bearings such asrollers 36 (Fig. 2) may be interposed between block 36 and the bottom ofpocket 32 to facilitate this sliding movement. A shoulder bolt 38secures the end of stub shaft 26 to the end of block 36 so that thelatter is carried with the stub shaft during reciprocation, butpermitting free rotative movement of these parts relative to oneanother.

At the right end of the doctor support beam (see Fig. 4) a portion 49 ofsuch beam is cut away to provide space for a bearing similar to thatjust described, as well as for the installation of the reciprocatingmotor to be described below. More specifically, stub shaft 28 at thisend of the doctor is provided with an end portion 42 of reduced diameterrotatably received within the cylindrical bore of a bearing block 44whose outer profile is square (see Fig. so as to slide within theupwardly open box support 46 of a support bracket 48 bolted or otherwisesecured to frame member l2. As in the case of the bearing at theopposite side of the machine, a shoulder bolt 56 passes freely throughan aperture in the end of block 44 and is threaded into shaft 28, aslight clearance being provided between the end of this shaft and theinner end wall of the block to permit free rotation of shaft 28 therein.Anti-friction rollers 52 support the block 44 upon the bottom wall ofthe box 46. Thus, the bearing blocks, the doctor blade support beam, theblade support and the blade may be reciprocated freely as a unitlaterally of the machine, while the support beam and parts carriedthereby may additionally be rotated to a limited extent to enable theblade to be withdrawn from the surface of roll l4. Moreover, theupwardly-open box-like support 32 and 46 permit the entire doctorassembly to be lifted out and replaced in the identical position withrespect to the roll [4.

-The manner in which the doctor support is periodically andautomatically reciprocated across the face of roll M will now bedescribed, it being understood that the purpose of such reciprocation isto prevent the formation of localized ridges or imperfections in eitherthe roll or the doctor blade, as might occur if the same point on thedoctor were continuously in contact with the same zone of the roll, orif a cyclic relation existed between roll and blade. Stub shaft 28 isprovided with an annular groove 54 which receives an upwardly opencrosshead 56 (Fig. 4) provided with laterally extending ears to whichare secured as by nut 58 the ends of a pair of drive rods 68 extendinginside the hydraulic motor 62, and which may receive sliding supportfrom a pair of laterally extending ears 54 (Fig. 5) preferably integralwith the square 'box structure 46. Since drive rods 60 are spacedequally on opposite sides of the stub shaft 28, it is clear that areciprocation of such rods by the motor 62 will cause the entire doctorsupport structure to slide easily back and forth across the face of rollI4 Without binding, and that the doctor blade itself is free to rotateto a limited extent in its axial bearings, either to accommodate forslight eccentricities in the roll M, or to enable the blade to bewithdrawn from the surface of the roll for changing or for otherreasons.

Additionally, it will be observed that since the square bearing blocks36 and 44 are received within upwardly open box formations 32 and 46,and cross-head 56 passes beneath the stub shaft 28, the entire doctorstructure, including bearing blocks 36 and 44, can easily be lifted awayfrom its support and drive means when such operation is necessary,without in any way disturbing the bolted support brackets or the drivemotor mounting, or the angular relation between the roll surface and thedoctor blade when the parts are replaced. This is a very valuablefeature particularly when it is necessary to change the clothing on themachine; for example, the Fourdrinier wire carried by a breast roll.

Figs. 6 and '7 illustrate the application of the improved form of doctordrive as applied to a double doctor arrangement for use on a top pressroll. Since the arrangements for the two doctors are duplicates of oneanother, only that for the lower of the pair (as seen in Fig. '7) willbe described in detail. The top press roll is indicated by numeral 64,and is supported as by bearings 66 and 68 mounted upon the oppositemachine frames, one of which is shown at 10, in the usual pivotedjournal frames or supports 14 (Fig. 7), whose purpose is to permit alimited swinging of the press roll 64 about the axle 16, thereby topress against the lower roll 18 (or upon an interposed felt) with aregulated pressure.

Hydraulically reciprocating drive motor for the lower doctor assembly isbolted to swinging journal frame 14 as by support bolts 82. Theoperating rods 84 of the motor, two in number, are here again spacedequally on opposite sides of the doctor operating shaft 86, andconnected thereto by a cross-head 88. Unlike the previous embodiment,however, the combination of sliding. and rotating movement of the doctoris achieved by journalling the same as at 96 within opposed cylindricalpockets 92 and 94 secured to the support frames, said pockets beingsufficiently deep to accommodate a limited amount of sidewisereciprocation of the doctor assembly. The operating shaft 86 passes fromthe crosshead 88 through an aperture in frame member 14.

The above arrangement is duplicated for the upper doctor assembly,except that in this case the motor and doctor supports are mounted upona pair of pillow blocks 96 and 98 respectively secured as by keywaysupon the upper surfaces of the swinging journal frames, bolsters I00 andH12 providing the necessary bearing support for the doctor assembly andfor the hydraulic motor. Since it is obviously impossible with thisarrangement to lift the entire doctor assembly bodily out of itsmounting, as was done in the previously described arrangement, thedoctor blades and their supports are here shown as secured boltedbrackets such as indicated at I84 (Fig. 6), which enable the doctorsupport to be removed bodily when occasion requires. However, thesedoctors, like those previously described, are capable of the freeswinging movement toward and away from press roll '64 by virtue of thecross-head connections between the doctor operating shafts and therespective hydraulic motors.

In accordance with the invention, a specialized form of hydraulicreciprocating drive motor is provided to causethediesired'l'slatcralitraverse of the doctor, blade support.

As best shown in "Figs. v8;and:.9,: thedoctor is connected to .across-head I06 secured 'around central shaft I.08.carrying at. its outerends hydraulic pistons IIO, .I I2. These pistons are provided'with ,cupleathers .I I4 and are adaptedto oscillate ina pairof cylinders I I6, .8having inlet passages I20, I22, respectively, .at their ends connectedoneatzatime itoa valvechamber I24 in which oscillates an; automatic:shuttle :element I26 controlling-the passage of. pressure liquid froman inlet I28'to passages I20, I22,;alternately.

A passage I30 leads to exhaust or relief. The shuttle valve I26 isguided .byiforming'a recess I62 in it into which astoppin I34-engages.

This shuttle valve ifurther :has arecess I36 :in

communication alternately iwiththe passages I20 and I22.

In operation pressure liquid, preferably oil'under. pressure, is:passedfromthe inlet. I28to the recess I36 and thence to either cylinderH6, 8 through passage I20 or passage I22. In the position shown in Fig.8, this pressure liquid can pass to passageway I22 in the cylinder blockto displace the piston I I2 at the outer end of its stroke inwardlyfromtheouten end of its cylinder, driving piston I I towards the outerend of itscylinder.

Liquid behind the piston I I0 can escape by passage I 20 intotheVaIVe-chamber I24 and thence through outlet port I38 communicatingwith the exhaust I30.

As the piston I I2 subject to pressure from the passage I22, reaches itsend position, a groove I40 in it communicating with an :axial passageI42 in the piston head, comes .intocoincidence with a groove I44 in thecylinder communicating with passage I46 leading to the space I48 behindthe shuttle valve I26 thus flicking it across so that the pressure inletI 28 now communicates through recess I 36 with the passage I20 causingthe piston elements H0, H2, to move back in the opposite directioncarrying with them the crosshead I06 attached to the doctor.

It is obvious that instead of forming the shuttle valve chamber I24containing the shuttle valve I26 within a unitary casting containing thecylinders II6, I I8, this may if desired be formed as a separate unitconnected with the passages I20, I22 and I46, I50 respectively byconnection pipes.

Chamfers I52 are formed at the ends of the valve so that the valve facescontrolling ports I54 and I56 of passages I20 and I22 are only veryslightly wider (by a few thousandths of an inch) than the ports I54 andI56. The recess I36 is slightly longer than the shortest distancebetween the ports I54 and I56 so as to ensure that one port is slightlyopen to pressure liquid before the other finally closes during movementof the valve.

Thus during operation there will be little danger of the valve stoppingin an intermediate position since although closure of the port I56 forexample during movement of the valve from right to left will prevent anyfurther feed of liquid through the port I56 and through passages I22 andI46 to the space I48, nevertheless the port I54 will by this time beopen to pressure liquid so as to cause movement of the pistons H0 and H2from left to right to cause displacement of liquid from the right handend of the cylinder I I8, first through passages I42, I44 to space I48and then through port I56 to space I48 whereby to ensure completion ofthe movement of the shuttle valve from'right to :left. :In thisrconnectionfitristo'he noted that the righthand outlet port I39 does notopen until after theport I56-hasopenedto continue through the passageI42 whose outlet in the cylinder H6 is notclosed until the piston I I0approaches its mid stroke.

.It will be appreciated that the hydraulic oscillating gear-of thepresent inventioncan be built .compactly and'with .a minimum of exposed;mov- .ing partsand that, in operation, the rate-of oscillation can bereadily adjusted and that since the movement of the doctordependsauponthe val- .umetic displacement (of the operating liquid -,fed

to .the pistons, a steadily progressive movement of thedoctor across theroll gislachieved.

A valuable feature of the operating gearof the present :invention is itsreliability since stoppage of a doctor in a paper making machine isliable to give riseto considerable damage and expensive .repairsas wellas loss of production.

In order to prevent the reciprocating motion of the doctor blade fromoccurring when the roll being doctored is at a standstill, which wouldtend to cause local wear upon the roll surface along atransverse line,the doctor motors .of any of the above arrangements may be provided witha control which is sensitive to the rotation of the breast or pressroll. ,Asshown in Fig. '10, such a control may comprise any knownorconvenient typeof hydraulic pump,.suchas-gear type pump I62 drivenfrom the rollbeing doctored, either by a frictional contact wheelengaging the face or sideof the roll, or by pulley or gear drive, and

connected to supply pressurefiuidthrough a duct I64 from a sump I66 andto a valve generally designated by I68. This valve maypomprisea spoolI10 shiftable against the pressure of a spring I12 to open the supplyline I14 of main hydraulic fluid to the doctor motor 62, whenever thepressure of fluid from pump I62 exceeds a predetermined amount. A safetyor relief valve I16 of conventional construction may be provided to passexcess oil pumped by pump I62 through a drain line I18 and back to sumpI66. Thus whenever roll I4 (or any equivalent roll being doctored) comesto a standstill, the pressure in line I64 will drop to a point at whichspring I12 will shift spool I10 to the right and close the supply lineI14, causing a cessation of the reciprocatory movement of the doctor.Upon resumption of rotation of the roll I4, pump I62 will cause abuild-up of pressure behind spool I10 sufficient to shift the spool toits Fig. 10 position, whereupon reciprocation of the doctor blade willagain ensue.

It will be seen from the above specification that I have provided anapparatus satisfying all of the objects of my invention in a relativelysimple and highly efficient manner, but obviously many changes andmodifications may be made in the specific details of constructionwithout departing from the spirit of the invention as defined in theappended claims.

I claim:

1. Doctor blade mechanism comprising: a rigid doctor blade support; apair of axially aligned stub shafts rigidly secured, one at each end ofsaid support; a pair of integral bearing members each rotatablyreceiving and enclosing one of said stub shafts with an ordinary journalfit, said bearing members having polygonal exterior cross-section, and apair of supports slidably receiving said bearing members, said supportscomprising troughs conforming to the exterior cross-section of saidbearing members, the upper sides of said troughs being open to permitremoval of the bearing members therefrom.

2. Doctor blade mechanism according to claim 1 including meanspenetrating said stub shafts for securing said bearing members to saidstub shafts against axial separation.

3. Doctor blade mechanism according to claim 1 in which one of said stubshafts has a circumferential groove adjacent the inner end of itsbearing member; a cross-head having a semicircular cutaway portion inits upper side engaging said groove, and means for reciprocating saidcrosshead.

4. Doctor blade mechanism according to claim 3 includin meanspenetrating said stub shafts for securing said bearing members to saidstub shafts against axial separation.

5. Doctor blade mechanism comprising: a rigid doctor blade support; apair of axially aligned stub shafts rigidly secured at each end of saidsupport; a bearing for each of said stub shafts, each of said bearingsproviding for simultaneous reciprocation and rotation of said stubshafts therein, a reciprocating hydraulic motor, and means including aconnection acting in a plane containing the axis of said stub shafts forconnecting said motor to one of said shafts to reciprocate said support,said connecting means being rotatably free of said stub shafts.

6. Doctor blade mechanism as set forth in claim 5 in which the hydraulicmotor has at least one piston mounted coaxially with the stub shafts.

7. Doctor blade mechanism comprising: a roll to be doctored; a doctorblade support adjacent said roll; a hydraulic motor for reciprocatingsaid support; a line supplying fluid to said motor;

a normally closed valve in said line; a pump driven by the rotation ofsaid roll, and means connecting said pump to said valve for opening thesame when the roll is rotated.

8. Doctor blade mechanism comprising a rigid doctor blade support, apair of axially aligned stub shafts rigidly secured one at each end ofsaid support, a pair of bearing members each rotatably receiving andenclosing one of said stub shafts, said bearing members having polygonalexterior cross-sections and a pair of supports slidably receiving saidbearing members, said supports comprising open troughs conforming to theexterior cross-section of said bearing members, one of said stub shaftshaving a circumferential groove adjacent the inner end of its bearingmember, a cross-head having a semicircular cut-away port-ion in itsupper side engaging said groove and means for reciprocating saidcross-head.

9. Doctor blade mechanism according to claim 8, including means forsecuring said bearing members to said stub shafts against axialseparation.

WILLIAM LYON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,243,049 Dewey Oct. 16, 19171,312,009 Thrift Aug. 5, 1919 1,798,887 Kutter Mar. 31, 1931 2,417,796Happ Mar. 18, 1947 FOREIGN PATENTS Number Country Date 588,998 GreatBritain June 9, 1947

